ABS Computer

This solid-state component evaluates wheel speed signals, and calculates allowable wheel slip for optimum braking. In order to determine optimum wheel slip precentages, the ABS computer monitors inputs from the wheel speed sensors, brake switch, and brake actuator. After making this calculation, it controls wheel circuit hydraulic pressure. When a wheel sensor signals excessive wheel deceleration (imminent lockup), the ABS computer first sends a signal that tells the brake actuator to isolate that hydraulic wheel circuit. If excessive wheel deceleration continues, the ABS computer signals the brake actuator to reduce the hydraulic pressure in that wheel circuit. After reducing pressure, the wheel accelerates; when acceleration reaches a preset level, the ABS computer signals the brake actuator to increase wheel circuit pressure. This action again causes wheel deceleration, and the control cycle begins over. In addition to being the "brain" of the ABS, the ABS computer tests and monitors itself and the anti-lock system using a defined program.